Probablity Of Life

From: Ray Dickenson <r.dickenson.nul>
Date: Mon, 9 Apr 2007 11:42:22 +0100
Fwd Date: Mon, 09 Apr 2007 08:04:26 -0400
Subject: Probablity Of Life
Hello List
Just realized there was a mention of 'others' in last message -
www.virtuallystrange.net/ufo/updates/2007/apr/m07-003.shtml
but forgot to do estimate of probability of life - on Earth or
anywhere.
Recently read that carbon element is 12th in abundance on Earth
(carbon is what Earth life is made of) - but that's now. Records
say that carbonaceous and other meteorites have been falling on
Earth for billions of years* so we know that carbon must
have been rarer on Earth in the past. How much rarer? Let's
conservatively say a few times rarer - so random events had
smaller chances of involving carbon molecules.
[We know non-organic mixtures can produce 'organic' molecules
(urea and suchlike) in the lab - first done by Miller (Chicago)
in 1953]
Yet from John Gribbin's 'Stardust' we learn that the mnemonic
for the most common elements in the wider Universe, is CHON -
Carbon, Hydrogen (& Helium), Oxygen and Nitrogen (not in that
order); he also describes the giant clouds of organic molecules,
up to and including DNA/RNA precursors, that are being detected
in deep space.
Even phosphorus, needed for RNA/DNA build, is about 20 times
more common ** in the Cosmos than in Earth's oceans, where
life is 'assumed' to have begun.
We can see at a glance the probability is that life began
elsewhere long before it had a chance to start on Earth. How
much more likely? Co-incidentally Asimov calculated that life
was 9 times to 81 times more likely to have developed first
around stars closer to Galactic center - just because they are
older. And we now find 'dwarf galaxies' scattered around us
which also turn out to be 'metallic' and therefore much older
than the Sun.
We could find that Asimov was not only right, but by an even
larger ratio than he'd thought.
References:
* 40 x 10^6 kg per year material falls as dust and meteorites
http://geolmag.geoscienceworld.org/cgi/content/extract/140/2/234
** Meteorites Supplied Earth Life with Phosphorus - Pasek
http://www.spaceref.com/news/viewpr.html?pid=14872
Cheers
Ray D
Listen to 'Strange Days... Indeed' - The PodCast
See:
http://www.virtuallystrange.net/ufo/sdi/program/